Bright pigments are incorporated in products that can have added value if capable of reflecting light with sparkles like those of stars, and examples of the products include paints used for painting automobiles, inks used in writing instruments, and cosmetics such as foundations and lipsticks. The use of a glass flake as a substrate of a bright pigment is known to provide superior appearance features such as high brightness and clear sparkles. There is also a commercially-available bright pigment that exhibits a specific color by means of interference color caused by a titanium oxide layer formed on the substrate of the pigment.
A proposed approach for allowing a bright pigment to exhibit a color with enhanced vividness is to deposit fine metal particles on the surface of the bright pigment and exploit a color formed by surface plasmon resonance of the fine metal particles.
Patent Literature 1 discloses bright pigments each produced by bringing a specific lamellar pigment into contact with a colloidal metal solution to deposit fine metal particles on the lamellar pigment. Example 4 of Patent Literature 1 is an example of bright pigment production, in which fine gold particles (colloidal gold particles) are deposited on a red pigment constituted by glass flakes whose surfaces are coated with a titanium oxide layer. Colloidal gold particles have traditionally been known as a red-color former and, in the above example, the use of colloidal gold particles enhances the vividness of the red pigment. Also in other examples presented in Patent Literature 1, fine gold particles are used as a red-color former for improving the color exhibited by lamellar pigments (Examples 1 to 3, and 6).
In Example 6 of Patent Literature 1, a bright pigment is produced by depositing fine gold particles on a blue lamellar pigment (titanated mica). Also in this example, the color exhibited by the fine gold particles is confirmed to be red. Referring to the table which collectively shows the results for the examples, it is seen that the improvement in vividness is smaller in Example 6 where the color (blue) exhibited by the lamellar pigment is different from the color (red) exhibited by the fine gold particles than in other examples (Examples 1 to 5) where the color exhibited by the metal oxide layer is the same as the color formed by surface plasmon resonance.